I was brought up in Japan and I was taught that w and wh are pronounced differently. But after I came to the US I learned that they mostly sound the same.

Now I watched this Youtube video where Craig Ferguson apparently misspoke Prince of Wales as Prince of Whales and the audience laughed.

It looked like Craig (who is from Scotland) was comfortably distinguishing two sounds. Is it a trait of Scottish English that it distinguishes w and wh? Or is it that even in the US the sounds w and wh are distinguished when they form a minimal pair like Wales and whales? (i.e. in the case of what, there's no word wat, so you don't have to pronounce h in what; but to distinguish Wales and whales you need to pronounce h.)

Hi Yuji! You remember my grandfather in Scotland who dropped his cigarette at the first talkimg movie :) He would certainly have distinguished "Wh" and "W" very clearly. Scottish talking is a bit strange: as you know it is very "thick" and "different." However, the Scots are (or were!) terribly "correct" upright conservative people with correct, careful enunciation. Do you know what I mean? So while Scottish is strange and guttural-sounding, it is known for being correctly, accurately, enunciated. Yes, those two sounds are quite distinct. Try to listen to a Sean Connery talk.
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Joe BlowJun 25 '11 at 5:51

As a Scot, I can confirm that in general, we do clearly aspirate the "wh" sound, so 'Wales' and 'whales' are very distinctly pronounced (and heard).
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scottishwildcatJun 25 '11 at 20:40

1

Craig Ferguson does make the distinction between /w/ and /ʍ/ (the two "w" sounds) in his Scottish dialect, but I can guarantee you that most or all of the people in the crowd did not laugh because of his pronunciation — they laughed because they picked up on the pun. Only the Southern American prestige dialect makes the distinction in the US.
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KosmonautJun 26 '11 at 21:57

Just to really throw a spanner in the works, in New Zealand English "wh" is sometimes pronounced "f". This is a source of some controversy.
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Optimal CynicJul 9 '11 at 15:47

@OptimalCynic - it's pronounced (and sometimes spelt) that way in and around Aberdeen as well.
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neilSep 28 '11 at 11:21

Background

Both consonants are "labio-velar approximants", with the w being "voiced" and the wh being "voiceless".

Merger

According to the article, you are correct about the regions where the distinction has been lost and where it remains; it remains in Scotland, but throughout most of the United States, the two sounds have merged into the voicedw:

The merger is essentially complete in England, Wales, the West Indies, Australia, New Zealand, and South Africa, and is widespread in the United States and Canada. In accents with the merger, pairs like wine/whine, wet/whet, weather/whether, wail/whale, Wales/whales, wear/where, witch/which etc. are homophonous. The merger is not found in Scotland, Ireland (except in the popular speech of Dublin, although the merger is now spreading more widely), and parts of the U.S. and Canada.

(emphasis added)

This map from Wikipedia shows a rough approximation of the regions in which the contrast between the sounds is the greatest:

Other Examples

The character Stewie from Family Guy, who is voiced in a very stuffy, grandiloquent accent, puts a great emphasis on the wh sound, a point which is made fun of in this video.

My own family is an example of this merger in action. My parents, especially my mother, speak the sounds distinctly, but my siblings and I do not. She was an English teacher, and we've had discussions about how our wh laziness irritates her. We insisted that it's not just laziness, but that the dialect has changed, and apparently this research shows that is actually true.

Thanks for the nice answer. So apparently, people in the region where wine and whine merged can still distinguish the sound, right? In Japan the sounds R and L are taken to be the same, and very few can distinguish them. But judging from the laugh of the audience, people in the US still can distinguish W and WH.
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YujiJun 25 '11 at 16:25

@Yuji. They've merged for me (even though I'm in the Irish midlands), but I can certainly distinguish them.
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TRiGSep 24 '11 at 20:16

@Yuji: I'm English, and I certainly can't distinguish 'w' and 'wh', because there is no standard distinction.
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MarcinOct 19 '11 at 10:39

@Marcin Thanks, that's interesting. So you don't discern the difference in Craig's pronunciation in the video ... interesting. Of course I can't distinguish R and L as a Japanese, so it's not surprising to me in some sense, but W and WH are very easy to distinguish to the Japanese ear.
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YujiOct 19 '11 at 10:44

The pronunciation of "wh" is very much debated. According to the region you are in, the "wh" is pronounced differently. Certain accents pronounce it "w", in a process called "wine-whine merger", while some still pronounce it as "hw".
Originally, the "wh" was pronounced "hw". This can be explained due to its history( i.e. "who" in Old English was spelt "hwa")

I reckon Craig Ferguson was just playing on this, except in the direct opposite, by pronouncing "Wales" as "Whales". Usually, "whale" is pronounced "wale", and so, Craig Ferguson may have been making a deliberate mistake.

It's also worth noting that in parts of Scotland, the distinction goes even further. In Aberdeenshire, the "hw" sound has become even more distinct, and is now pronounced "f" (at least, when speaking in the local dialect, known as "Doric"). So words like "what" are pronounced more like "hwit" in the Central Belt part of Scotland, but are pronounced "fit" in Aberdeen.

This gives rise to the joke about the child trying to work out which boot goes on which foot, and asking "Fit fit fits fit fit?" (what foot fits what foot).

It is certainly true that a merger is underway in Canada. I myself differentiate between w and wh as I grew up listening to my Scottish parents, and I think in general Canadians in the 50s and 60s spoke this way. It wasn't until the 90s when my own children began to make fun of me, especially in relation to our own family name (White) that I even realized that things were changing.

It is always disturbing to see one's own heritage disappearing and to have fruitless conversations with one's own children over such things. Now I have in a way acquiesced somewhat to avoid embarrassment, as I am a teacher, and find that it is a constant struggle to decide whether to stick to what I think is correct, or to go with what the majority feel is the correct way. I am talking about many other pronunciations, not just this w vs. wh dilemma.

Alas, this isn't entirely correct, and I find it to differ from region to region. As a personal example, I pronounce which and witch differently. Furthermore, if I heard someone say, "The Prince of [hwales]" (as opposed to [wails]) I would understand that he means the big marine mammal.
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Kaz DragonOct 19 '11 at 9:40

You reverse the 'h' and 'w' when pronouncing 'wh'?
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MarcinOct 19 '11 at 10:36

@Marcin: "wh", when distinguished from "w", has pronunciation written by [hw] by the international phonetic alphabet. It's written with "hw" in the Old English, as the link en.wikipedia.org/wiki/Phonological_history_of_wh cited above says.
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YujiOct 19 '11 at 10:42

@Marcin Yes. It comes out sounding quite airy. On the downside, jokes "where's the soap?" and "how do you get two whales in a car?" no longer work.
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Kaz DragonOct 19 '11 at 13:30

@KazDragon: Both of those jokes are lost on me.
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MarcinOct 19 '11 at 13:42